Conventional RFID transponders comprise a voltage limiter, e.g. in form of a voltage clamp to prevent the output of an RFID rectifier from exceeding a certain voltage. Such a limiter is necessary to prevent damage to internal components of the RFID transponder by excessive voltage and to limit the supply voltage range for the operation of the RFID transponder and its electronic circuits. The limiters conventionally used in RFID transponders or RFID circuits often lack accuracy and a voltage level to clamp makes it difficult to guarantee that a clamp voltage is greater than the minimum allowed supply voltage or less than the maximum allowed supply voltage.
The patent application US 2014/0268964 A1 discloses for instance a multi-stage programmable rectifier wherein each rectifier stage can include a first transistor and a switch connected thereto. There, a threshold voltage of the first transistor can be programmed through selection of one of a plurality of voltages available at the switch.
Implementation of numerous switches in a multi-stage programmable rectifier is rather sophisticated. Moreover, limiting of a DC output voltage of a programmable rectifier requires a rather extensive calibration or tuning of said rectifier.